Conventionally in a manufacturing process of a semiconductor device, an object to be processed such as a semiconductor wafer is carried into a vacuum processing apparatus and then a predetermined process is executed on the semiconductor wafer under a depressurized atmosphere. In general, plural kinds of processes, e.g., film formation, etching, heating, and the like, are performed on the wafer in different processing apparatuses to complete the semiconductor device.
In such case, if the wafer is transferred through a plurality of processing apparatuses separately installed from each other, a processing chamber (or a load-lock chamber) of each processing apparatus is exposed to the atmosphere whenever the wafer is carried into and out of each processing apparatus. By this, a considerable amount of time is required for evacuating the processing chambers (load-lock chambers), leading to a deterioration in throughput. Further, there may be a process in which a formation of a natural oxide film or moisture on a surface of the wafer should be avoided depending on the type of the process, e.g., when performing a series of film forming processes.
For such reason, there has been developed a so-called cluster type processing system in which a polygonal common vessel for defining a common transfer chamber under a vacuum state is provided in a center thereof; and a plurality of vacuum processing apparatuses are disposed around and connected with the common vessel in a radial shape. In this processing system, a plurality of processes can be performed on the wafer by transferring the wafer through the plural processing apparatuses without exposing a processing chamber of each processing apparatus to the atmosphere. Through a plurality of cluster type processing systems, a large quantity of wafers are transferred at a low speed by an automated guided vehicle (AGV or RGV) or the like.
Nowadays, there are ever-increasing demands for high density, high integration and small quantity batch production of many different kinds of the semiconductor devices. Moreover, it is also required to further improve a processing efficiency and increase the kinds of the processes. Therefore, it becomes necessary to connect a larger number (e.g., five or more) of processing apparatuses than conventionally required (e.g., three), to the common vessel in the cluster system. Further, additional processing apparatuses may be required to be installed at an already prepared cluster type processing system.
In such a case, there can be conceived a scheme of increasing a size of the polygonal common vessel of the cluster type processing system to connect more processing apparatuses around a periphery thereof, or connecting a plurality of common vessels to each other. However, an enlargement of the size of the common vessel requires a large-scale increase in strength (thickness) of a ceiling and a bottom wall of the vessel since an inner space of the common vessel is in a vacuum state, which, as a result, proves to be unrealistic. Further, in case the plurality of processing apparatuses are connected to the polygonal common vessel in the radial shape, there are left lots of dead spaces between the processing apparatuses, resulting in a poor utilization of space.
To address such problems, there have been proposed processing systems such as disclosed in Japanese Patent Laid-open Publication Nos. 4-288812, 6-349931, 8-119409 and 2001-2241. In such processing systems, an elongated common vessel of a rectangular shape is provided, and a plurality of processing apparatuses are connected to longer sidewalls of the common vessel. Further, a moving part having a rotatable, flexible and compressible/extensible transfer arm for mounting thereon a wafer is installed in the common vessel to be rectilinearly movable in a longitudinal direction of the common vessel.
Such processing systems are superior, in view of efficiency in space utilization, to the aforementioned processing system which includes the processing apparatuses radially disposed around the common vessel, but has less freedom in the installation of the additional processing apparatuses therein. For instance, in case one or more processing apparatuses need to be added to a processing system already installed, it is difficult to quickly respond to meet such need.
Furthermore, the moving part is moved in the common vessel in the longitudinal direction thereof to transfer the wafer. However, it is not preferable to install an elevation mechanism for loading and unloading the wafer in the transfer arm of the moving part and to connect a cable for supplying a driving power (to the transfer arm or the elevation mechanism) to the moving part. This is because there may be produced particles due to sliding motion of the elevation mechanism and impurities to be introduced from the cable or the like, which eventually will lead to complicating the structure and the scaling up of the moving part.